Star Formation Efficiency in Nearby Galaxies Revealed with a New CO-to-H2 Conversion Factor Prescription
學年 112
學期 1
出版(發表)日期 2024-01-12
作品名稱 Star Formation Efficiency in Nearby Galaxies Revealed with a New CO-to-H2 Conversion Factor Prescription
著者 Yu-Hsuan Teng; I-Da Chiang; Karin M. Sandstrom; Jiayi Sun; Adam K. Leroy; Alberto D. Bolatto; Antonio Usero; Eve C. Ostriker; Miguel Querejeta; Jérémy Chastenet; Frank Bigiel; Médéric Boquien; Jakob den Brok; Yixian Cao; Mélanie Chevance; Ryan Chown; Dario Colombo; Cosima Eibensteiner; Simon C. O. Glover; Kathryn Grasha; Jonathan D. Henshaw; María J. Jiménez-Donaire; Daizhong Liu; Eric J. Murphy; Hsi-An Pan; Sophia K. Stuber; Thomas G. Williams
著錄名稱、卷期、頁數 The Astrophysical Journal 961(1)
摘要 Determining how the galactic environment, especially the high gas densities and complex dynamics in bar-fed galaxy centers, alters the star formation efficiency (SFE) of molecular gas is critical to understanding galaxy evolution. However, these same physical or dynamical effects also alter the emissivity properties of CO, leading to variations in the CO-to-H2 conversion factor (αCO) that impact the assessment of the gas column densities and thus of the SFE. To address such issues, we investigate the dependence of αCO on the local CO velocity dispersion at 150 pc scales using a new set of dust-based αCO measurements and propose a new αCO prescription that accounts for CO emissivity variations across galaxies. Based on this prescription, we estimate the SFE in a sample of 65 galaxies from the PHANGS–Atacama Large Millimeter/submillimeter Array survey. We find increasing SFE toward high-surface-density regions like galaxy centers, while using a constant or metallicity-based αCO results in a more homogeneous SFE throughout the centers and disks. Our prescription further reveals a mean molecular gas depletion time of 700 Myr in the centers of barred galaxies, which is overall three to four times shorter than in nonbarred galaxy centers or the disks. Across the galaxy disks, the depletion time is consistently around 2–3 Gyr, regardless of the choice of αCO prescription. All together, our results suggest that the high level of star formation activity in barred centers is not simply due to an increased amount of molecular gas, but also to an enhanced SFE compared to nonbarred centers or disk regions.
語言 en_US
ISSN 1538-4357; 0004-637X
期刊性質 國外
收錄於 SCI
國別 USA
出版型式 ,電子版,紙本

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